Fuel cells are devices that convert the fuel and oxidant to electrical energy. Most efficient fuel cells use pure hydrogen as the fuel and oxygen as the oxidant. Unfortunately use of pure hydrogen has a number of known disadvantages not the least of which is its relatively high cost. Consequently, attempts have been made to operate fuel cells using other than the pure hydrogen as the fuel. For example, attempts have been made to use hydrogen rich gas mixtures obtained from steam reforming methanol as a fuel cell feed. These attempts, however, have not resulted in a practical system because carbon monoxide which is present in such gas mixtures degrades cell performance, even in relatively low concentrations.
It is an object of the present invention therefore to treat a CO-containing, hydrogen rich gas mixture to lower the CO content of the mixture to render it more suitable for use in fuel cell systems.
It is another object of the present invention to provide a method for lowering the CO content of a hydrogen rich gas stream in a single step.
It is another object of the present invention to provide a method for reducing the CO content of a hydrogen rich gas stream which is energy efficient.
Another object of the present invention is to provide a fuel cell system in which a CO-containing, hydrogen rich gas stream is subjected to an adsorption step and in which the carbon monoxide is preferentially adsorbed thereby lowering the carbon monoxide content of the gas mixture to below about 10 ppm to provide a substantially CO free, hydrogen rich gas stream which is subsequently fed to the fuel cell for use therein.